The U.S. military is reviewing options for a unilateral strike in Pakistan in the event that a successful attack on American soil is traced to the country’s tribal areas, according to senior military officials.

Ties between the alleged Times Square bomber, Faisal Shahzad, and elements of the Pakistani Taliban have sharpened the Obama administration’s need for retaliatory options, the officials said. They stressed that a U.S. reprisal would be contemplated only under extreme circumstances, such as a catastrophic attack that leaves President Obama convinced that the ongoing campaign of CIA drone strikes is insufficient.

“Planning has been reinvigorated in the wake of Times Square,” one of the officials said.

At the same time, the administration is trying to deepen ties to Pakistan’s intelligence officials in a bid to head off any attack by militant groups. The United States and Pakistan have recently established a joint military intelligence center on the outskirts of the northwestern city of Peshawar, and are in negotiations to set up another one near Quetta, the Pakistani city where the Afghan Taliban is based, according to the U.S. military officials. They and other officials spoke on the condition of anonymity because of the sensitivity surrounding U.S. military and intelligence activities in Pakistan.

The “fusion centers” are meant to bolster Pakistani military operations by providing direct access to U.S. intelligence, including real-time video surveillance from drones controlled by the U.S. Special Operations Command, the officials said. But in an acknowledgment of the continuing mistrust between the two governments, the officials added that both sides also see the centers as a way to keep a closer eye on one another, as well as to monitor military operations and intelligence activities in insurgent areas.

Obama said during his campaign for the presidency that he would be willing to order strikes in Pakistan, and Secretary of State Hillary Rodham Clinton said in a television interview after the Times Square attempt that “if, heaven forbid, an attack like this that we can trace back to Pakistan were to have been successful, there would be very severe consequences.”

Obama dispatched his national security adviser, James L. Jones, and CIA Director Leon Panetta to Islamabad this month to deliver a similar message to Pakistani officials, including President Asif Ali Zardari and the military chief, Gen. Ashfaq Kiyani.

Jones and Panetta also presented evidence gathered by U.S. law enforcement and intelligence agencies that Shahzad received significant support from the Pakistani Taliban.

The U.S. options for potential retaliatory action rely mainly on air and missile strikes, but could also employ small teams of U.S. Special Operations troops already positioned along the border with Afghanistan. One of the senior military officials said plans for military strikes in Pakistan have been revised significantly over the past several years, moving away from a “large, punitive response” to more measured plans meant to deliver retaliatory blows against specific militant groups.